For an explanation, see the main splats page
The principles of gases
- Around 1620, Jan Baptista van Helmont coined the new word 'gas', taking it from the Flemish word for 'chaos', suggesting he had some notion of what gases are.
- In 1661 Robert Boyle published his 'Sceptical Chymist' and stated his law for ideal gases relating volume to pressure, and made a number of other key points.
- In his 'Sceptical Chymist', Robert Boyle made reference to chemical elements, acids and alkalis, and offered a corpuscular theory of matter, all in one year.
- An ideal gas obeys the law described in the gas equation. Real gases approximate reasonably well to Boyle's law, Charles' Law and the combined gas law.
- The first person to propose that gases were made of particles was Daniel Bernoulli, who realized that assuming a gas made of particles explained its behaviour.
- The behaviour of gases may be explained by using the kinetic molecular theory which considers the gas molecules as independent particles, able to move freely.
- In 1848, James Joule calculated the average velocity of gas molecules from kinetic theory. It contained the first numerical results from the kinetic theory.
- The diffusion of gases obeys Graham's law of diffusion, which says that the square root of the density of the gas is inversely proportional to its velocity.
- The reactions between gases follow Gay-Lussac's law, which states that the volume ratios of the reactants and the products will involve small whole numbers.
- Avogadro's hypothesis proposed that equal volumes of gas under the same conditions of temperature and pressure, contained the same number of molecules.
- In 1772, Joseph Priestley discovered that the volume of air decreases when an electric spark passes through it, but did not explain the effect.
- Avogadro's constant is the number of molecules of a compound with a mass in grams equal to the molecular weight, and as a gas, occupies 22.4 litres at STP.
- In the 1890s, Rayleigh found that nitrogen prepared from air had a different density from nitrogen which was prepared chemically. The difference was argon.
- In 1798, Humphry Davy was involved in treating people with gases. During this work, he saw the effects of laughing gas (nitrous oxide), and wrote about them.
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